DESCRIPTION (Adapted from applicant's description): Preterm (less thatn 37 weeks gestation), premature rupture of membranes (PROM) accounts for 40-60% of all preterm deliveries and is the largest contributor of infant morbidity and mortality. PROM is highly correlated with admissions to the NICU (Neonatal Intensive Care Unit) and with patient characteristics of smoking during pregnancy, mid trimester placental bleeding, and chorioamnionitis. These characteristics suggest that reactive oxygen species (ROS) play an important contribution to PROM, and is the working hypothesis for this R03 proposal. Previous work by the principal investigator has demonstrated, using an in vitro model system for human fetal membranes, that an ROS, hypochlorous acid, damages the amniochorion in a dose-dependent manner. Moreover, when these membranes were pretreated with an antioxidant mixture of Vitamins C and E, the hypochlorous acid-induced damage was prevented. This proposal continues this mechanistic investigation into other major ROS, including superoxide, hydroxyl radical, peroxynitrite, hydrogen peroxide and nitric oxide. For each ROS, pretreatment with Vitamins C and E will also determine whether these antioxidants prevent damage induced by these other major ROS. Endpoints for study focus upon alteration and damage to Collagen I, the strongest collagen in the amniochorion. Specifically, Collagen I immunocytochemistry and release of Collagen I fragment will be determined. In addition, use of a membrane dynamometer will measure tensile strength of the membrane after ROS exposure and when pretreated with antioxidants.